Two-stage fermentative hydrogen production process comprising dark fermentation and photofermentation
followed by gas upgrading is studied from the technical and economic points of view. It is
assumed that a conceptual hydrogen plant is connected to a sugar factory so that technical sucrose
solutions produced there (raw juice, thick juice and molasses) can be used as fermentation feedstocks.
Process data needed for the study are based on the results of a recently completed research project and in
the techno-economic assessment of hydrogen production, data acquired in the sugar industry are taken
into account. A parametric study of the cost of hydrogen production from molasses shows that the total
cost is highly sensitive to the capital and operating costs of the photofermentation stage. Prospects of
cost reduction through further development of the two-stage fermentative process are discussed.